Spockrates:
If I may: we must never forget that there is no potency in God. That includes, in my opinion, the “possible.” We don’t know what God has created. We only know the past few thousand years. Prior to these recent years, we have fossil and geological records. Are we not discovering things new to us every day somewhere in the universe? IMHO, God is instantiating every possibility as we speak.
Why doesn’t God create monsters? Well, He has. If the findings in the fossil records are the remains of actual creatures! Then, consider the preparation of the Earth for the likes of us and our intense need for fossil fuel. Consider artists’ depictions of ancient critters on the land and in the seas. If you can think of something He hasn’t thought of, that may be worth millions to you. We are to some unfathomable extent hampered by our own limitations.
A number of your inquiries are unanswerable by men. The Church has, throughout its life, considered many things, and as best as it could, in earlier times, provided answers to those questions. But, many will remain unanswered and unanswerable until they are answered.
God bless,
jd